light - switch to light theme
dark - switch to dark theme
This way, the theme can quickly be changed so that terminal text can be
read on crappier projectors for presentaitons, classes, etc.
hl command accepts syntax type and optionally a filename as arguments.
If a filename is given, it will syntax highlight the file and place the
contents on the clipboard. If no file is given, it will use the contents
of the clipboard.
